Steer axle with integrated directional control

ABSTRACT

A steer-by-wire steering system having an I-beam and a steering gear housing coupled therewith. An input shaft assembly may be at least partially disposed within the steering gear housing. A steering knuckle having a kingpin boss and an output shaft having a first end at least partially disposed within the kingpin boss. A second end of the output shaft at least partially disposed within the steering gear housing.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/398,928 filed on Sep. 23, 2016, and is a divisional of U.S. patentapplication Ser. No. 15/712,765 filed on Sep. 22, 2017, which are fullyincorporated by reference herein in their entirety.

BACKGROUND

The present disclosure relates to a vehicle steering system;particularly to a steer axle with integrated directional control. In aconventional steering system directional control is obtained throughsteering gears mounted remotely on a vehicle frame. The steering gearscontrol vehicle direction by providing a desired wheel turn anglethrough a series of mechanical and/or hydraulic linkages on a steeraxle. Conventional steering systems may include a steering columnmechanically connected to the steering gear; the steering gear mayoperate a pitman arm connected to a drag link transverse to an axlebeam; and the drag link may be connected to a steering arm connected toa first steering knuckle on which a wheel is mounted. Conventionalsteering systems may also include a tie rod connecting the firststeering knuckle with a second steering knuckle. Hydraulic and/orelectric actuators may also be included in a conventional steeringsystem.

Conventional steering systems are disadvantaged by their complexity,weight, and Ackerman steering geometry error. The presently disclosedsubject matter describes a steering system that simplifies the steeraxle control system, reduces system complexity and weight, reducesassembly time, and in at least one embodiment, eliminates Ackermansteering geometry error. The presently disclosed subject matter alsoprovides a platform for integrating autonomous vehicle driving controls.

SUMMARY

The present disclosure provides for a steer-by-wire steering system. Inone embodiment, the steer-by-wire steering system includes an I-beamhaving a steering gear housing coupled therewith. An input shaftassembly may be at least partially disposed within the steering gearhousing. Further, the steer-by-wire system may include a steeringknuckle having a kingpin boss. An output shaft may have a first end atleast partially disposed within the kingpin boss, and a second end atleast partially disposed within the steering gear housing.

In another embodiment, there steer-by-wire system may include a steeringgear housing coupled with a knuckle. An input shaft assembly may be atleast partially disposed within the steering gear housing. An outputshaft may have a first end at least partially disposed within thesteering gear housing, and a second end coupled with an I-beam.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings are incorporated herein as part of thespecification. The drawings described herein illustrate embodiments ofthe presently disclosed subject matter, and are illustrative of selectedprinciples and teachings of the present disclosure.

However, the drawings do not illustrate all possible implementations ofthe presently disclosed subject matter, and are not intended to limitthe scope of the present disclosure in any way.

FIG. 1 schematically depicts a vehicle steering system according to anembodiment of the presently disclosed subject matter;

FIG. 2 illustrates a portion of the vehicle steering system according toFIG. 1;

FIG. 3 illustrates a portion of a vehicle steering system according toanother embodiment of the presently disclosed subject matter;

FIG. 4 illustrates a side-elevation of a portion of the vehicle steeringsystem according to FIG. 3;

FIG. 5 illustrates a portion of a vehicle steering system according toanother embodiment of the presently disclosed subject matter;

FIG. 6 illustrates a side-elevation of a portion of the vehicle steeringsystem according to FIG. 5;

FIG. 7 illustrates a knuckle according to an embodiment of the presentlydisclosed subject matter;

FIG. 8 illustrates a cross-section of the knuckle according to FIG. 7;

FIG. 9 illustrates a cross-section of a knuckle according to anotherembodiment of the presently disclosed subject matter; and

FIG. 10 illustrates a knuckle according to still another embodiment ofthe presently disclosed subject matter.

DETAILED DESCRIPTION OF EMBODIMENTS

It is to be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific devices,assemblies, systems and processes illustrated in the attached drawings,and described in the following specification are simply exemplaryembodiments of the inventive concepts defined herein. Hence, specificdimensions, directions or other physical characteristics relating to theembodiments disclosed are not to be considered as limiting, unlessexpressly stated otherwise. Also, although they may not be, likeelements in various embodiments described herein may be commonlyreferred to with like reference numerals within this section of theapplication.

Certain embodiments of a steering system 100 are utilized with heavyvehicles such as commercial trucks. However, the steering system 100 maybe utilized with, but is not limited to use with, military vehicles,off-highway vehicles, passenger vehicles, electric vehicles, andautonomous or semi-autonomous driving vehicles.

As illustrated in FIG. 1, in an embodiment, the steering system 100 maybe a steer-by-wire system. The steering system 100 may include asteering input 102 by which a vehicle operator may enter a desired wheelturn-angle into the steering system 100. The steering input 102 mayinclude, but is not limited to, an autonomous or semi-autonomous sensoryprocessing apparatus, a steering wheel, a joystick, or a twin leversteering apparatus. The steering system 100 also includes a controller104 electronically coupled with the steering input 102. The controller104 interfaces with and receives an electrical signal from the steeringinput 102. The controller 104 processes the signal received from thesteering input 102 and outputs a signal to a first directional controlassembly 106, 206, 306 electronically coupled with the controller 104.The controller 104 may also provide road feedback to the vehicleoperator by transmitting a signal to the steering input 102. In anembodiment where the steering input 102 is a steering wheel, thecontroller 104 may provide road feedback to the vehicle operator byapplying torque to the steering wheel.

As illustrated in FIG. 2, in an embodiment, the first directionalcontrol assembly 106 comprises a steering gear housing 110. The steeringgear housing 110 may be coupled with a first end 108A of an I-beam 108via a plurality of fasteners 112. The I-beam may also be referred to asa beam axle or solid axle. In another embodiment, the steering gearhousing 110 may be welded to the I-beam first end 108A. In yet anotherembodiment, the steering gear housing 110 may be formed integral andunitary with the I-beam first end 108A. The first directional controlassembly 106 may include an input shaft assembly 132 disposed inside thesteering gear housing 110. In an embodiment, the input shaft assembly132 is coupled with an electric motor (not depicted). The electric motorcontrols the input shaft assembly 132. The electric motor iselectronically coupled with the controller 104, such that the electricmotor may respond to signals from the steering input 102. The electricmotor may receive a signal from the controller 104 which determines theturn angle output by the first directional control assembly 106. Theelectric motor may be coupled with a first end of the input shaftassembly 132. In another embodiment, the input shaft assembly 132 may becontrolled by a hydraulic system (not depicted).

In other embodiments, the first directional control assembly 106 inputassembly may include, but is not limited to, a worm gear assembly, ahydraulic assisted gear assembly, or an electronic assisted gearassembly.

The electric motor controls a series of mechanical and/or hydraulicsystem linkages within the steering gear housing 110 which are coupledwith the output shaft 114. The output shaft 114 may replace a kingpin ina conventional steering system. The output shaft 114 is coupled with aknuckle 116 such that the output shaft 114 and the knuckle 116 may pivottogether in response to input from the electric motor. In an embodiment,the knuckle 116 includes a kingpin boss 118. The output shaft 114 is atleast partially disposed in the kingpin boss 118 and an aperture 119through the housing 110. The first directional control assembly 106further acts as an I-beam head, of the I-beam 108, in the kingpin joint.

In the embodiment illustrated in FIG. 2, a second directional controlassembly 107 may be disposed at a second end 108B of the I-beam 108. Thesecond directional control assembly 107, similar to the firstdirectional control assembly 106, may include an input shaft assembly(not depicted) coupled with a second electric motor (not depicted). Thesecond electric motor may be coupled with a first end of the input shaftassembly. The second electric motor is electronically coupled with thecontroller 104, such that the second electric motor may respond tosignals from the steering input 102. The second electric motor drives aseries of mechanical and/or hydraulic linkages drivingly coupled with anoutput shaft (not depicted). The output shaft is coupled with a knuckle(not depicted) such that the output shaft and the knuckle may pivottogether in response to input from the second electric motor.

In the embodiment illustrated in FIGS. 1 and 2, where the first andsecond directional control assemblies 106, 107 are integrated on eitherside of the I-beam 108, the necessity of a tie-rod assembly and theassociated ball joints (not depicted) is obviated. Utilizing independentfirst and second directional control assemblies 106, 107 also eliminatesthe Ackerman steering error by allowing direct independent control ofeach wheel turn angle.

In another embodiment, as illustrated in FIGS. 3 and 4, directionalcontrol assemblies 206, 207 may be integrated into the respectivesteering knuckle. The first directional control assembly 206 maycomprise a steering gear housing 210. The steering gear housing 210 maybe formed unitary with a knuckle 216. In another embodiment, thesteering gear housing 210 may be coupled with the knuckle 216. Theknuckle 216 includes a kingpin boss 218. A first end of an output shaft214 may be disposed in and rotatably coupled with the kingpin boss 218.A second end of the output shaft 214 may be disposed in an I-beam head230.

The first directional control assembly 206 may include an input shaftassembly 232 disposed inside the steering gear housing 210. The inputshaft assembly 232 is coupled with an electric motor (not depicted). Theinput shaft assembly 232 may comprise, but is not limited to, a wormgear assembly, a hydraulic assisted gear assembly, or an electronicassisted gear assembly. The electric motor controls a series ofmechanical and/or hydraulic linkages within the housing 210 which arecoupled with the output shaft 214. The output shaft 214 may replace akingpin in a conventional steering system. The output shaft 214 isrotatably coupled with the knuckle 216 such that the knuckle 216 maypivot around the output shaft 214 in response to input from the electricmotor. The output shaft 214 is coupled with the I-beam head 230 so thatthere is no rotation therebetween. Further, the output shaft 214transmits torque to the I-beam head 232. Utilizing the output shaft 214as a kingpin eliminates the need for separate bushings/bearings between.

The output shaft 214 may comprise a plurality of gear teeth (notdepicted) on the outer surface thereof. In another embodiment, theoutput shaft 214 may be coupled with a gear (not depicted) such as asector gear. The output shaft 214 may be in meshed engagement with theinput shaft assembly 232.

In another embodiment, as illustrated in FIGS. 5 and 6, a directionalcontrol assembly 306 may be integrated into a steering knuckle 316. Thedirectional control assembly 306 is similar to the first directionalcontrol assembly 206. However, where the first directional controlassembly steering gear housing 210 and input assembly is orientedtransverse to their respective wheel assembly spindle (not depicted), asteering gear housing 310 of a directional control assembly 306 andinput assembly (not depicted) are oriented parallel with a spindle 340.In other, words, the steering gear housing 310 is oriented parallel witha longitudinal axis of an I-beam at a zero turn angle. In anotherembodiment, not depicted, the steering gear housing may be oriented atany angle with respect to said I-beam at a zero turn angle.

The steering gear housing 310 may share a first wall portion (notdepicted) with a kingpin boss 318 and a second wall portion (notdepicted) with an ear 317 of a steering knuckle 316. Because thesteering gear housing 310 may comprise a first and second wall portionshared with the steering knuckle 316, the directional control assembly306 may comprise a lighter weight and/or more compact alternative to thefirst directional control assembly 206.

A first end of an output shaft 314 may be disposed in and rotatablycoupled with the kingpin boss 318. A second end of the output shaft 314may be disposed in an I-beam head 330. The first directional controlassembly 306 may include an input shaft assembly (not depicted) disposedinside the steering gear steering gear housing 310. The input shaftassembly is coupled with an electric motor (not depicted). The inputshaft assembly may comprise, but is not limited to, a worm gearassembly, a hydraulic assisted gear assembly, or an electronic assistedgear assembly. The electric motor controls a series of mechanical and/orhydraulic linkages within the steering gear housing 310 which arecoupled with the output shaft 314. The output shaft 314 may replace akingpin in a conventional steering system. The output shaft 314 isrotatably coupled with the knuckle 316 such that the knuckle 316 maypivot around the output shaft 314 in response to input from the electricmotor. The output shaft 314 is coupled with the I-beam head 330 so thatthere is no rotation therebetween.

In yet another embodiment (not depicted), a first directional controlassembly coupled with a first steering knuckle or an I-beam, asdescribed supra, may be utilized in conjunction with a tie-rod assemblycoupled with a second steering knuckle. In this embodiment, only onedirectional control assembly is necessary to output a turn angle at twowheel assemblies.

Conventionally, steering knuckles are produced through a forging method.In embodiments where a directional control assembly housing and inputassembly are integrated into a steering knuckle as disclosed supra, itmay be necessary or beneficial to produce the steering knuckles througha casting process. The casting method may require, or benefit, fromincreasing the dimensions of the steering knuckle. However, steeringknuckle spindles are defined by industry standards.

Therefore, in an embodiment, as illustrated in FIGS. 7 and 8, a caststeering knuckle 416 may comprise a cast knuckle body 442 and aseparately manufactured spindle 440 coupled therewith. The knuckle body442 may comprise knuckle ears 444, 446 and a kingpin boss 418. Theknuckle boss 418 may comprise a flange 448 having a surface 450 where aninput assembly and housing (not depicted) may be coupled. The kingpinboss 418 further comprises an aperture 452 disposed through the flangesurface 450. The knuckle body 442 also comprises a recess 454 and anopening 458 coaxial with the aperture 452. The recess 454 comprises adiameter larger than the diameter of the opening 458 creating a shoulder455 where the recess 454 and the opening 458 meet.

The spindle 440 may comprise a tapered shaft having a smaller diameterat an outboard end 441 and a larger diameter at an inboard end 443. Theinboard end 443 of the spindle 440 may include a flange 456. Inaddition, the spindle 440 may comprise a fluid conduit 460 extendingfrom the inboard end 443 to the outboard end 441. In assembling thesteering knuckle 416, the spindle 440 may be inserted through theaperture 452, the recess 454, and the opening 458. The spindle 440 maythen be press fit into recess 454 and the opening 458 until the flange456 abuts the shoulder 455.

In another embodiment, as illustrated in FIG. 9, a cast steering knuckle516 may comprise a knuckle body 542 and a separately manufacturedspindle 540 coupled therewith. As described in U.S. Pat. No. 6,916,030,the knuckle body 542 may be insert-cast about the spindle 540. Thespindle 540 may include multiple flanges 556 and/or projections 557whereby a mechanical interlock is achieved between the cast knuckle body542 and the spindle 540. The disclosure of U.S. Pat. No. 6,916,030 isincorporated herein by reference in its entirety.

In yet another embodiment, a steering knuckle may comprise an as-castunitary component comprising austempered ductile iron, also known asADI. In still another embodiment, a steering knuckle may comprise anas-cast unitary component wherein the spindle diameter has beenincreased to, match the drive axle standard for spindle diameter.

In another embodiment, as illustrated in FIG. 10, a cast steeringknuckle 616 may comprise a knuckle body 642 and a separatelymanufactured spindle 640 coupled therewith. The spindle may comprise abolt flange 656 by which the spindle 640 may be mechanically fastenedto, or coupled with, the knuckle body 642 via a plurality of mechanicalfasteners 660.

While various embodiments of the presently disclosed subject matter havebeen described above, it should be understood that they have beenpresented by way of example, and not limitation. It will be apparent topersons skilled in the relevant arts that the disclosed subject mattermay be embodied in other specific forms without departing from thespirit or essential characteristics thereof. The embodiments describedabove are therefore to be considered in all respects as illustrative,not restrictive.

What is claimed:
 1. A steering knuckle for a vehicle, comprising: aknuckle body including a kingpin boss formed therein; and a spindlehaving an outboard end and an inboard end, wherein the knuckle bodyabuts at least a portion of the spindle.
 2. The steering knuckle ofclaim 1, wherein the knuckle body is formed by a casting process.
 3. Thesteering knuckle of claim 1, wherein the knuckle body further includesat least one knuckle ear formed thereon.
 4. The steering knuckle ofclaim 1, wherein the kingpin boss further includes a flange formedthereon.
 5. The steering knuckle of claim 4, wherein the flange of thekingpin boss includes a surface configured to receive at least one of aninput assembly and a housing thereon.
 6. The steering knuckle of claim5, wherein the kingpin boss further includes an aperture formed in thesurface of the flange.
 7. The steering knuckle of claim 6, wherein theknuckle body further includes at least one of a recess and an openingformed therein.
 8. The steering knuckle of claim 7, wherein the spindleis press fit into the at least one of the recess and the opening formedin the knuckle body.
 9. The steering knuckle of claim 7, wherein atleast one of the recess and the opening is formed coaxial with theaperture formed in the flange of the kingpin boss.
 10. The steeringknuckle of claim 7, wherein a diameter of the recess is larger than adiameter of the opening.
 11. The steering knuckle of claim 7, wherein ashoulder is formed at a juncture of the recess and the opening.
 12. Thesteering knuckle of claim 1, wherein a diameter of the outboard end ofthe spindle is smaller than a diameter of the inboard end of the spindleforming a tapered shaft.
 13. The steering knuckle of claim 1, whereinthe inboard end of the spindle includes a flange formed thereon.
 14. Thesteering knuckle of claim 13, wherein the flange of the inboard end ofthe spindle abuts a shoulder formed in the knuckle body.
 15. Thesteering knuckle of claim 13, wherein the flange of the inboard end ofthe spindle is coupled to the knuckle body by at least one mechanicalfastener.
 16. The steering knuckle of claim 1, wherein the spindleincludes a fluid conduit extending from the inboard end to the outboardend thereof.
 17. The steering knuckle of claim 1, wherein the knucklebody is cast about the at least a portion of the spindle.
 18. Thesteering knuckle of claim 1, wherein a mechanical lock is formed betweenthe knuckle body and the spindle.
 19. The steering knuckle of claim 18,wherein the mechanical lock is formed by the knuckle body cast about theinboard end of the spindle.
 20. The steering knuckle of claim 1, whereinthe knuckle body is formed from an austempered ductile iron.